Solar-powered pump

A solar-powered pump is a pump running on electricity generated by photovoltaic panels or the radiated thermal energy available from collected sunlight as opposed to grid electricity or diesel run water pumps.^[1] The operation of solar powered pumps is more economical mainly due to the lower operation and maintenance costs and has less environmental impact than pumps powered by an internal combustion engine (ICE). Solar pumps are useful where grid electricity is unavailable and alternative sources (in particular wind) do not provide sufficient energy.

A photovoltaic solar powered pump system has three parts:

• solar panels.
• the controller
• the pump

The solar panels make up most (up to 80%) of the systems cost.^{[citation needed]} The size of the PV-system is directly dependent on the size of the pump, the amount of water that is required (m³/d) and the solar irradiance available.

The purpose of the controller is twofold. Firstly, it matches the output power that the pump receives with the input power available from the solar panels. Secondly, a controller usually provides a low voltage protection, whereby the system is switched off, if the voltage is too low or too high for the operating voltage range of the pump. This increases the lifetime of the pump thus reducing the need for maintenance.

Voltage of the solar pump motors can be AC (alternating current) or DC (direct current). Direct current motors are used for small to medium applications up to about 3 kW rating, and are suitable for applications such as garden fountains, landscaping, drinking water for livestock, or small irrigation projects. Since DC systems tend to have overall higher efficiency levels than AC pumps of a similar size, the costs are reduced as smaller solar panels can be used.

Finally, if an alternating current solar pump is used, an inverter is necessary that changes the direct current from the solar panels into alternating current for the pump. The supported power range of inverters extends from 0.15 to 55 kW and can be used for larger irrigation systems. However, the panel and inverters must be sized accordingly to accommodate the inrush characteristic of an AC motor.

Solar powered water pumps can deliver drinking water as well as water for livestock or irrigation purposes.^[1] Solar water pumps may be especially useful in small scale or community based irrigation, as large scale irrigation requires large volumes of water that in turn require a large solar PV array.^[2] As the water may only be required during some parts of the year, a large PV array would provide excess energy that is not necessarily required, thus making the system inefficient.

Solar PV water pumping systems are used for irrigation and drinking water in India. The majority of the pumps are fitted with a 2000 watt - 3,700 watt motor that receives energy from a 4,800 Wp PV array. The 5hp systems can deliver about 124,000 liters of water/day from a total of 50 meters setoff head and 70 meters dynamic head. By 30 August 2016, a total of 1,20,000 solar PV water pumping systems have been installed in INDIA. ^[3] in this system it produces 19M.H.W and 26 ton carbon dioxide

Solar Carport (Parkiran Mobil Tenaga Surya)

            Pemanfaatan listrik tenaga surya salah satunya bisa dengan memanfaatkan lahan parkiran mobil/motor. Solar modul berfungsi sebagai atap sekaligus penghasil listrik. Hal itu akan membuat parkiran lebih bermanfaat dan mampu menghasilkan energy dengan tidak mengurangi fungsi dasarnya sebagai tempat parkir mobil. Hanya saja harga yang ditawarkan tentu lebih tinggi dibandingkan dengan Carport yang biasanya. Hal itu sepadan dengan manfaat yang diperoleh. Listrik yang dihasilkan bisa untuk charging mobil listrik ataupun untuk System On Grid/Off grid Solar Power Plan. Dibawah ini adalah contoh desain dari Carport yang belum sempat diproduksi oleh saya.

Manfaat jahe ( Benefits of Ginger)

Jahe merupakan tanaman dengan rasa agak pedas, rimpang jahe biasanya dipanen dan digunakan. Rimpang merupakan batang tempat akar muncul. Jahe memiliki banyak manfaat bagi kesehatan, seperti membantu merangsang fungsi pankreas dan sistem pencernaan.

Tanaman ini juga berguna untuk mengobati penyakit pernapasan, seperti batuk atau flu, dan sebagai obat penenang untuk mengurangi rasa sakit tubuh. Kandungan Vitamin C dan B6 yang sangat baik, bersama dengan mineral seperti potassium, membuat jahe menjadi obat alami yang baik untuk berbagai penyakit. Jahe bahkan memiliki sifat antioksidan.

Air jahe bisa disajikan dengan campuran bahan dapur lainnya, namun kayu manis dan jus lemon bahan yang paling sering ditambahkan dalam minuman ini. Ada beberapa manfaat kesehatan dalam minuman jahe, seperti yang dilansir dari laman Step To Health, (Senin, 24/7/17).

1. Mempercepat metabolisme
Jahe dikenal dengan sifat termogeniknya. Itulah mengapa jahe sangat bagus untuk mempercepat metabolisme Anda dan mengurangi lemak pada orang-orang yang gemuk atau kelebihan berat badan.

2. Memperbaiki pencernaan
Akar ini mengandung konsentrasi serat tinggi, sehingga meningkatkan fungsi usus Anda.
Ini juga membantu tubuh menyerap lebih banyak nutrisi sambil membantu menghilangkan semua racun yang dapat menyebabkan pembengkakan dan ketidaknyamanan pada perut.

3. Antioksidan yang baik
Jahe merupakan sumber vitamin dan mineral yang banyak. Sifat antioksidannya bermanfaat bagi kesehatan jantung dan membantu melawan pengerasan serta penyempitan arteri, sehingga membantu aliran darah.

Untuk kecantikan, jahe bisa digunakan untuk menghilangkan ketombe, melembapkan tubuh, dan mencegah rambut kering, mencegah kerontokan rambut dan mendorong pertumbuhan.

4. Menjaga kadar kolesterol
Air jahe bisa membantu tubuh Anda mengatur kadar kolesterol jahat (LDL). Peningkatan kadar kolesterol dalam aliran darah dapat menyumbat arteri dan menyebabkan masalah kardiovaskular.

5. Membantu mengurangi rasa sakit
Air jahe dapat membantu mengurangi rasa sakit dari daerah tertentu di tubuh. Hal ini membuatnya sangat cocok jika Anda mengalami nyeri sendi, nyeri otot, linu, dan radang sendi.

Gejala skizofrenia

Gejala skizofrenia dibagi menjadi dua kategori, yaitu negatif dan positif. Gejala negatifskizofrenia menggambarkan hilangnya sifat dan kemampuan tertentu yang biasanya ada di dalam diri orang yang normal. Sebagai contoh,

• Keengganan untuk bersosialisasi dan tidak nyaman berada dekat dengan orang lain sehingga lebih memilih untuk berdiam di rumah.
• Kehilangan konsentrasi.
• Pola tidur yang berubah.
• Kehilangan minat dan motivasi dalam segala aspek hidup, termasuk minat dalam menjalin hubungan

Perubahan pola tidur, sikap tidak responsif terhadap keadaan, dan kecenderungan untuk mengucilkan diri merupakan gejala-gejala awal skizofrenia. Terkadang gejala tersebut sulit dikenali orang lain karena biasanya berkembang di masa remaja sehingga orang lain hanya menganggapnya sebagai fase remaja.

Ketika penderita sedang mengalami gejala negatif, dia akan terlihat apatis dan datar secara emosi (misalnya bicara monoton tanpa intonasi, bicara tanpa ekspresi wajah, dan tidak melakukan kontak mata). Mereka juga menjadi tidak peduli terhadap penampilan dan kebersihan diri, serta makin menarik diri dari pergaulan. Sikap tidak peduli akan penampilan dan apatis tersebut bisa disalahartikan orang lain sebagai sikap malas dan tidak sopan. Hal ini sering kali memicu rusaknya hubungan penderita dengan keluarga ataupun dengan teman-temannya.

Gejala negatif skizofrenia bisa berlangsung beberapa tahun sebelum penderita mengalami episode akut pertama, yaitu ketika gejala menjadi parah dan kadang-kadang diikuti beberapa gejala positif.

Gejala positif skizofrenia terdiri dari:

• Halusinasi. Terjadi pada saat panca indera seseorang terangsang oleh sesuatu yang sebenarnya tidak ada. Fenomena halusinasi terasa sangat nyata bagi penderita. Contoh gejala halusinasi yang biasanya dialami oleh penderita skizofrenia adalah mendengar suara-suara.
• Delusi. Yaitu kepercayaan kuat yang tidak didasari logika atau kenyataan yang sebenarnya. Contoh gejala delusi bisa bermacam-macam. Ada penderita yang merasa diawasi, diikuti, atau khawatir disakiti oleh orang lain. Ada juga yang merasa mendapat pesan rahasia dari tayangan televisi. Gejala-gejala delusi semacam ini bisa berdampak kepada perilaku penderita skizofrenia.
• Pikiran kacau dan perubahan perilaku. Penderita sulit berkonsentrasi dan pikirannya seperti melayang-layang tidak tentu arah sehingga kata-kata mereka menjadi membingungkan. Penderita juga bisa merasa kehilangan kendali atas pikirannya sendiri. Perilaku penderita skizofrenia juga menjadi tidak terduga dan bahkan di luar normal. Misalnya, mereka menjadi sangat gelisah atau mulai berteriak-teriak dan memaki tanpa alasan.

Penting untuk mengenali gejala-gejala skizofrenia seperti di atas. Jika Anda atau keluarga Anda mengalami gejala-gejala tersebut, segera periksakan ke rumah sakit. Makin dini skizofrenia ditangani, maka peluang sembuh menjadi makin tinggi.

Pengertian Skizofrenia

Skizofrenia adalah gangguan mental kronis yang menyebabkan penderitanya mengalami delusi, halusinasi, pikiran kacau, dan perubahan perilaku. Kondisi yang biasanya berlangsung lama ini sering diartikan sebagai gangguan mental mengingat sulitnya penderita membedakan antara kenyataan dengan pikiran sendiri.

Penyakit skizofrenia bisa diidap siapa saja, baik laki-laki maupun perempuan. Kisaran usia 15-35 tahun merupakan usia yang paling rentan terkena kondisi ini. Penyakit skizofrenia diperkirakan diidap oleh satu persen penduduk dunia.

Menurut data Kementerian Kesehatan Republik Indonesia (Kemenkes) yang dipublikasikan pada tahun 2014, jumlah penderita skizofrenia di Indonesia diperkirakan mencapai 400 ribu orang.

Di Indonesia, akses terhadap pengobatan dan pelayanan kesehatan jiwa masih belum memadai. Akibatnya, sebagian besar penduduk di negara ini, terutama di pelosok-pelosok desa, kerap memperlakukan pasien gangguan jiwa dengan tindakan yang tidak layak seperti pemasungan.

Penyebab skizofrenia

Sebenarnya para ahli belum mengetahui apa yang menjadi penyebab skizofrenia secara pasti. Kondisi ini diduga berisiko terbentuk oleh kombinasi dari faktor psikologis, fisik, genetik, dan lingkungan.

Diagnosis dan pengobatan skizofrenia

Jika Anda memiliki kerabat atau teman-teman yang menunjukkan gejala skizofrenia, segera bawa ke dokter. Makin cepat penyakit ini terdeteksi, semakin baik. Peluang sembuh penderita skizofrenia akan lebih besar jika diobati sedini mungkin.

Karena skizofrenia merupakan salah satu jenis gangguan mental, maka pemeriksaan harus dilakukan oleh dokter spesialis kejiwaan atau psikiater. Penyakit skizofrenia akan terdeteksi pada diri pasien jika:

• Mengalami halusinasi, delusi, bicara meracau, dan terlihat datar secara emosi.
• Mengalami penurunan secara signifikan dalam melakukan tugas sehari-hari, termasuk penurunan dalam produktivitas kerja dan prestasi di sekolah akibat gejala-gejala di atas.
• Gejala-gejala di atas bukan disebabkan oleh kondisi lain, seperti gangguan bipolar atau efek samping penyalahgunaan obat-obatan.

Dalam mengobati skizofrenia, dokter biasanya akan mengombinasikan terapi perilaku kognitif (CBT) dengan obat-obatan antipsikotik. Untuk memperbesar peluang sembuh, pengobatan juga harus ditunjang oleh dukungan dan perhatian dari orang-orang terdekat.

Meskipun sudah sembuh, penderita skizofrenia tetap harus dimonitor. Biasanya dokter akan terus meresepkan obat-obatan untuk mencegah gejala kambuh. Selain itu, penting bagi penderita untuk mengenali tanda-tanda kemunculan episode akut dan bersedia membicarakan kondisinya pada orang lain.

Bahaya dari Bahan Bakar Fosil (Dangerous off Fosil Fuel)

               Bahan bakar fosil seperti namanya adalah turunan dari tumbuhan dan hewan fosil yang berusia juta tahun. Ini terutama terbentuk dari sisa-sisa tanaman membusuk dan hewan dari zaman Karbon. Ketiga bahan bakar sumber batu bara,[ gas alam dan minyak / minyak membantu untuk memenuhi energi dan listrik tuntutan dunia saat ini.

Permintaan untuk energi tidak akan pernah dalam grafik menurun. Revolusi industri telah menunjukkan jalan dan itu masih berlangsungBahan bakar fosil adalah sumber energi utama tapi masih ketika lebih konsumsi terjadi menyebabkan dampak buruk seperti polusi udara. Pembakaran bahan bakar fosil melepaskan karbon dioksida, nitrogen monoksida, nitrogen dioksida, sulfur dioksida, karbon monoksida dan lain-lain yang memiliki konsekuensi parah pada habitat.

Mereka juga mempengaruhi kesehatan manusia. Mereka adalah sumber-sumber non-energi terbarukan karena mereka berasal dari fosil prasejarah dan tidak lagi tersedia jika pernah digunakan. Sumber mereka terbatas dan mereka menipis pada tingkat yang lebih cepat. Ketika diekstraksi itu menimbulkan kerusakan parah pada lanskap karena mereka harus menggali dari sumur bawah tanah.

Kekurangan Bahan Bakar Fosil

1. Lingkungan Bahaya: Polusi adalah kerugian yang besar yang terbentuk karena bahan bakar fosil. Ketika dibakar mereka memberikan karbon dioksida, gas rumah kaca yang merupakan aspek utama dari pemanasan global. Kenaikan suhu bumi telah mengakibatkan mencairnya es di kutub, banjir daerah dataran rendah, kenaikan permukaan air laut. Jika kondisi seperti itu menaklukkan muka bumi akan menghadapi perubahan radikal.

2. Kenaikan Harga : negara Tengah-timur memiliki cadangan besar minyak dan gas alam dan banyak negara lainnya juga tergantung pada mereka untuk pasokan konstan bahan bakar ini. Organisasi Negara-negara Pengekspor Minyak (OPEC) adalah sekelompok 13 negara termasuk Iran, Irak, Kuwait, Qatar, Arab Saudi dan UEA.

Mereka bertanggung jawab untuk 40 persen dari produksi minyak dunia dan memegang mayoritas cadangan minyak dunia, menurut Administrasi Informasi Energi (EIA). OPEC terus-menerus memantau volume minyak yang dikonsumsi dan kemudian menyesuaikan produksi sendiri untuk mempertahankan harga per barel yang diinginkan. Hasil ini dalam fluktuasi harga di seluruh dunia, menurut Departemen Energi AS.

3. Hujan Asam: Ketika dibakar, gas sulfur dioksida juga diproduksi yang merupakan faktor untuk hujan asam. Hujan asam menyebabkan kerusakan monumen terdiri dari bata atau kelereng, bahkan tanaman yang terpengaruh karena pengasaman tanah liat. Hasil penambangan batubara di perusakan lahan yang berlimpah dan juga membahayakan kehidupan penambang.

Gas alam menyebabkan bau jahat dan juga banyak masalah dengan transportasi. Transportasi minyak mentah menyebabkan tumpahan minyak atas lautan penalaran terhadap bahaya untuk kehidupan akuatik dengan mengurangi kandungan oksigen air.

4. Kesehatan Manusia Terkena: Lapisan ozon sedang usang karena pelepasan gas rumah kaca dari bahan bakar. Oleh karena itu, lubang ozon yang diciptakan dari mana sinar UV yang berbahaya masuk ke permukaan bumi yang mempengaruhi kehidupan manusia menyebabkan penyakit seperti kanker. melanin hadir dalam kulit bereaksi dengan radiasi gelombang tinggi ini. Kanker kulit adalah bentuk utama dari penyakit yang disebabkan karena reaksi sinar infra-merah dan hadir pigmen di kulit.

5. Terbarukan: Sebagai bahan bakar fosil yang diambil ke tingkat yang tidak terbatas itu adalah untuk memastikan bahwa mereka akan menguras beberapa hari atau yang lain.

Karena mereka tidak terbarukan ada kemungkinan bahwa biaya bahan bakar akan menghadapi kenaikan dalam waktu dekat. Ini akan mengambil jutaan tahun untuk menggantikan batu bara, dan minyak, dan kita menggunakan mereka dengan cepat. Ada jumlah terbatas bahan bakar ini tersedia dan kami tidak benar-benar yakin di mana batas itu.

6. Dampak terhadap Perairan Tumpahan Minyak: Bahan bakar fosil yang dibutuhkan dalam cadangan besar di mana pun tanaman mereka ditetapkan. Hal ini mengharuskan mereka untuk diangkut ke lokasi yang diinginkan melalui truk, kereta api, kapal laut atau pesawat.

Sering kita mendengar dari beberapa kebocoran di kapal tanker minyak atau kapal tenggelam mendapatkan jauh di bawah laut yang membawa minyak mentah untuk mendapatkan halus. Dampak dari ini adalah bahwa minyak mentah mengandung beberapa zat beracun yang bila dicampur dengan air menimbulkan bahaya serius bagi kehidupan air.

7. Pertambangan Batubara: Ekstraksi batubara dari daerah yang memiliki cadangan besar tidak hanya tugas yang sulit dan berbahaya, tetapi juga menimbulkan bahaya kesehatan bagi kehidupan beberapa pekerja yang bekerja di sana. Pertambangan batu bara menghancurkan wilayah yang luas tanah dan menghasilkan ketidak seimbangan ekologi.

8. Butuh Cadangan dalam Jumlah Besar : di pembangkit listrik tenaga batubara membutuhkan pasokan besar dan teratur batubara untuk menghasilkan sejumlah besar listrik secara konstan. Ini berarti mereka harus cadangan batubara hampir kereta-banyak bahan bakar di dekat pembangkit listrik untuk melaksanakan proses pembangkit listrik.

Hal ini diperlukan karena saat ini juga banyak negara bergantung pada batu bara sebagai sumber utama menghasilkan tenaga. Teknologi untuk mendapatkan lebih dari bumi mengalami kemajuan, tetapi mereka tidak tampaknya akan melakukan secepat permintaan kami tumbuh. Selain itu, sementara batubara jauh lebih banyak daripada minyak, ekstraksi batubara bisa sangat tidak aman, dan merusak lingkungan dalam skala besar, menyebabkan erosi, pengasaman lingkungan, dan perusakan lahan liar.

Meskipun bahan bakar fosil memenuhi energi dan bahan bakar kebutuhan kita, masih itu adalah saatnya untuk melihat ke depan untuk sumber terbarukan energi alternatif seperti turbin angin, panel surya, generator pasang surut dan kompos. Seperti yang dikatakan oleh orang besar, ada cukup untuk kebutuhan semua orang tapi tidak cukup untuk keserakahan semua orang.

Manfaat Energy Terbarukan (Profit of Renewable Energy)

Konsep energi terbarukan mulai dikenal pada tahun 1970-an, sebagai upaya untuk mengimbangi pengembangan energi berbahan bakar nuklir. Energi terbarukan juga dikenal sebagai sumber energi seperti dari sumber daya alam seperti angin, matahari, panas, hujan, panas bumi, dan air pasang yang cepat dipulihkan kembali secara alami, dan prosesnya berkelanjutan. Ada beberapa keuntungan dalam penggunaan energi jenis ini, antara lain:

Energi Terbarukan Tidak Merusak Lingkungan

Kita juga bisa berkontribusi dalam pencegahan pemanasan global dengan menggunakan energi terbarukan. Karena kandungan yang terdapat didalamnya tidak memberikan efek negatif terhadap lingkungan. Selain itu juga lingkungan tidak akan terancam keselamatannya jika manusia mulai berhenti untuk mengebor bahan bakar fosil.

Energi Terbarukan Bisa Dijadikan Sebagai Peluang Bisnis

Kita bisa memproduksi dan memanfaatkan lebih banyak energi dan menjual sisanya sebagai pendapatan sampingan. Negara Listrik biasanya menjual panel surya kepada perusahaan-perusahaan listrik. Selian itu juga masyarakat lebih tertarik memakai hasil produksi industri hijau.

Dibandingkan Dengan Fosil, Energi Terbarukan Lebih Aman

Hasil pembakaran bahan bakar fosil melepaskan karbon dioksida, nitrogen monoksida, nitrogen dioksida, sulfur dioksida, karbon monoksida dan lain-lain yang memiliki konsekuensi parah pada habitat. Mereka juga mempengaruhi kesehatan manusia. Hal ini sangat merugikan karena menambahkan biaya medis dan kerusakan pada properti.

Solar Street Light ( Lampu Penerangan Jalan Tenaga Surya)

Penerangan Jalan merupakan sarana yang menunjang pengendara kendaraan waktu malam hari. Keberadaan lampu penerangan jalan memang sangat dibutuhkan. Ada 2 macam berdasarkan sumber listriknya. Sebagai berikut :
1. Lampu penerangan dengan sumber grid/jaringan listrik PLN.
Biasanya lampu ini untuk daerah yang sudah memiliki sumber jaringan listrik. Baik di desa, perkotaan, jalan antar daerah, maupun jalan Tol memiliki tingkat keterangan/ Intensitas cahaya yang berbeda. Untuk system ini hanya memerlukan timer on off saja untuk menyalakan lampu di sore hari dan mematikan lampu di pagi hari. Atau bisa saja menggunakan saklar biasa yang dioperasikan manusia.

2. Lampu bersumber dari off grid ( dari Tenaga surya, angin ataupun kombinasi)
Lampu ini dikhususkan untuk daerah yang belum memiliki jaringan listrik ataupun yang menginginkan kemandirian sumber listrik. Untuk jumlah terbanyak, tenaga surya dirasa lebih efektif karena sumber energinya yang melimpah di siang hari dibandingkan dengan angin yang ada di daerah tertentu saja. Komponen yang dibutuhkan yaitu : Solar modul, Charge Controleer, Aki, Box battery, dan Lampu. Penambahan bracket juga diperlukan sebagai dudukan modul surya di bagian atas. Berikut ini contoh Gambarnya.

SNI(Standart Nasional Indonesia) telah mengatur tingkat keterangan di jalan dengan satuan Lux. Bina Marga Sebagai lembaga yang menerbitkan Aturan mengenai hal itu. Untuk mengetahui tingkat keterangan bisa diukur dengan Lux meter. Misalnya untuk jalan tol tingkat terangnya cahaya dijalan minimal 20 Lux. Sedangkan di jalan antar daerah cukup 10 Lux. 

PHOTOVOLTAIC SYSTEM GROUND-FAULT PROTECTION

PHOTOVOLTAIC SYSTEM GROUND-FAULT PROTECTION
When a photovoltaic system is mounted on the roof of a residential dwelling, NEC
requirements dictate the installation of ground-fault protection (detection and interrupting) devices (GFPD). However, ground-mounted systems are not required to have the
same protection since most grid-connected system inverters incorporate the required
GFPDs.
Ground-fault detection and interruption circuitry perform ground-fault current
detection, fault current isolation, and solar power load isolation by shutting down the
inverter. This technology is currently going through a developmental process, and it is
expected to become a mandatory requirement in future installations.
PV SYSTEM GROUNDING
Photovoltaic power systems that have an output of 50 V dc under open-circuit conditions are required to have one of the current-carrying conductors grounded. In electrical engineering, the terminologies used for grounding are somewhat convoluted and
confusing. In order to differentiate various grounding appellations it would be helpful
to review the following terminologies as defined in NEC Articles 100 and 250.
Grounded.Means that a conductor connects to the metallic enclosure of an electrical device housing that serves as earth.
Grounded conductor. A conductor that is intentionally grounded. In PV systems it
is usually the negative of the dc output for a two-wire system or the center-tapped
conductor of an earlier bipolar solar power array technology.
Equipment grounding conductor. A conductor that normally does not carry current
and is generally a bare copper wire that may also have a green insulator cover. The
conductor is usually connected to an equipment chassis or a metallic enclosure that
provides a dc conduction path to a ground electrode when metal parts are accidentally energized.
Grounding electrode conductor. A conductor that connects the grounded conductors
to a system grounding electrode, which is usually located only in a single location
within the project site, and does not carry current. In the event of the accidental
shorting of equipment the current is directed to the ground, which facilitates actuation of ground-fault devices.
Grounding electrode.A grounding rod, a concrete-encased ultrafiltration rate (UFR)
conductor, a grounding plate, or simply a structural steel member to which a grounding
ENTRANCE SERVICE CONSIDERATIONS FOR GRID-CONNECTED SOLAR POWER SYSTEMS 71
electrode conductor is connected. As per the NEC all PV systems—whether gridconnected or stand-alone, in order to reduce the effects of lightning and provide a
measure of personnel safety—are required to be equipped with an adequate grounding system. Incidentally, grounding of PV systems substantially reduces radiofrequency noise generated by inverter equipment.
In general, grounding conductors that connect the PV module and enclosure frames
to the ground electrode are required to carry full short-circuited current to the ground;
as such, they should be sized adequately for this purpose. As a rule, grounding conductors larger than AWG #4 are permitted to be installed or attached without special
protection measures against physical damage. However, smaller conductors are
required to be installed within a protective conduit or raceway. As mentioned earlier,
all ground electrode conductors are required to be connected to a single grounding
electrode or a grounding bus.
EQUIPMENT GROUNDING
Metallic enclosures, junction boxes, disconnect switches, and equipment used in the
entire solar power system, which could be accidentally energized are required to be
grounded. NEC Articles 690, 250, and 720 describe specific grounding requirements.
NEC Table 25.11 provides equipment grounding conductor sizes. Equipment grounding conductors similar to regular wires are required to provide 25 percent extra ground
current-carrying capacity and are sized by multiplying the calculated ground current
value by 125 percent. The conductors must also be oversized for voltage drops as
defined in NEC Article 250.122(B).
In some installations bare copper grounding conductors are attached along the railings that support the PV modules. In installations where PV current-carrying conductors are routed through metallic conduits, separate grounding conductors could be
eliminated since the metallic conduits are considered to provide proper grounding when
adequately coupled. It is, however, important to test conduit conductivity to ensure that
there are no conduction path abnormalities or unacceptable resistance values.

Wiring Design for Photovoltaic

Essentially solar power installations include a hybrid of technologies consisting of basic
ac and dc electric power and electronics—a mix of technologies, each requiring specific
technical expertise. Systems engineering of a solar power system requires an intimate
knowledge of all hardware and equipment performance and application requirements. In
general, major system components such as inverters, batteries, and emergency power
generators, which are available from a wide number of manufacturers, each have a
unique performance specification specially designed for specific applications.
The location of a project, installation space considerations, environmental settings,
choice of specific solar power module and application requirements, and numerous
other parameters usually dictate specific system design criteria that eventually form
the basis for the system design and material and equipment selection.
Issues specific to solar power relate to the fact that all installations are of the outdoor
type, and as a result all system components, including the PV panel, support structures,
wiring, raceways, junction boxes, collector boxes, and inverters must be selected and
designed to withstand harsh atmospheric conditions and must operate under extreme
temperatures, humidity, and wind turbulence and gust conditions. Specifically, the electrical wiring must withstand, in addition to the preceding environmental adversities,
degradation under constant exposure to ultraviolet radiation and heat. Factors to be
taken into consideration when designing solar power wiring include the PV module’s
short-circuit current (Isc) value, which represents the maximum module output when
output leads are shorted. The short-circuit current is significantly higher than the normal or nominal operating current. Because of the reflection of solar rays from snow, a
nearby body of water or sandy terrain can produce unpredicted currents much in excess
of the specified nominal or Isc current. To compensate for this factor, interconnecting
PV module wires are assigned a multiplier of 1.25 (25 percent) above the rated Isc.
PV module wires as per the NEC requirements are allowed to carry a maximum
load or an ampacity of no more than 80 percent; therefore, the value of currentcarrying capacity resulting from the previous calculation is multiplied by 1.25, which
results in a combined multiplier of 1.56.
The resulting current-carrying capacity of the wires if placed in a raceway must be
further derated for specific temperature conditions as specified in NEC wiring tables
(Article 310, Tables 310.16 to 310.18).
All overcurrent devices must also be derated by 80 percent and have an appropriate
temperature rating. Note that the feeder cable temperature rating must be the same as
that for overcurrent devices. In other words, the current rating of the devices should be
25 percent larger than the total sum of the amount of current generated from a solar
array. For overcurrent device sizing NEC Table 240-6 outlines the standard ampere
ratings. If the calculated value of a PV array somewhat exceeds one of the standard
ratings of this table, the next highest rating should be chosen.
All feeder cables rated for a specific temperature should be derated by 80 percent
or the ampacity multiplied by 1.25. Cable ratings for 60, 75, and 90°C are listed in
NEC Tables 310.16 and 310.17. For derating purposes it is recommended that cables
rated for 75°C ampacity should use 90°C column values. Various device terminals,
SOLAR POWER SYSTEM WIRING 69
such as terminal block overcurrent devices must also have the same insulation rating
as the cables. In other words, if the device is in a location that is exposed to a higher
temperature than the rating of the feeder cable, the cable must be further derated to
match the terminal connection device. The following example is used to illustrate
these design parameter considerations.
A wiring design example Assuming that the short-circuit current Isc from a PV
array is determined to be 40 A, the calculation should be as follows:
1PV array current derating = 40 ×1.25=50 A.
2Overcurrent device fuse rating at 75°C = 50 ×1.25=62.5 A.
3Cable derating at 75°C = 50 ×1.25=62.5. Using NEC Table 310-16, under the 75°C
columns we find a cable AWG #6 conductor that is rated for 65-A capacity. Because
of ultraviolet (UV) exposure, XHHW-2 or USE-2 type cable, which has a 75-A
capacity, should be chosen. Incidentally, the “–2” is used to designate UV exposure
protection. If the conduit carrying the cable is populated or filled with four to six
conductors, it is suggested, as previously, by referring to NEC Table 310-15(B)(2)(a),
that the conductors be further derated by 80 percent. At an ambient temperature of
40 to 45°C a derating multiplier of 0.87 is also to be applied: 75 A ×0.87 = 52.2 A.
Since the AWG #6 conductor chosen with an ampacity of 60 is capable of meeting
the demand, it is found to be an appropriate choice.
4By the same criteria the closest overcurrent device, as shown in NEC Table 240.6,
is 60 A; however, since in step 2 the overcurrent device required is 62.5 A, the AWG
#6 cable cannot meet the rating requirement. As such, an AWG #4 conductor must
be used. The chosen AWG #4 conductor under the 75°C column of Table 310-16
shows an ampacity of 95.
If we choose an AWG #4 conductor and apply conduit fill and temperature derating, then the resulting ampacity is 95 ×0.8×0.87 = 66 A; therefore, the required fuse
per NEC Table 240-6 will be 70 A.
Conductors that are suitable for solar exposure are listed as THW-2, USE-2, and
THWN-2 or XHHW-2. All outdoor installed conduits and wireways are considered to
be operating in wet, damp, and UV-exposed conditions. As such, conduits should be
capable of withstanding these environmental conditions and are required to be of
a thick wall type such as rigid galvanized steel (RGS), intermediate metal conduit
(IMC), thin wall electrical metallic (EMT), or schedule 40 or 80 polyvinyl chloride
(PVC) nonmetallic conduits.
For interior wiring, where the cables are not subjected to physical abuse, special
NEC code approved wires must be used. Care must be taken to avoid installation of
underrated cables within interior locations such as attics where the ambient temperature can exceed the cable rating.
Conductors carrying dc current are required to use color coding recommendations
as stipulated in Article 690 of the NEC. Red wire or any color other than green and
white is used for positive conductors, white for negative, green for equipment grounding, and bare copper wire for grounding. The NEC allows nonwhite grounded wires,
70 SOLAR POWER SYSTEM DESIGN CONSIDERATIONS
such as USE-2 and UF-2, that are sized #6 or above to be identified with a white tape
or marker.
As mentioned earlier, all PV array frames, collector panels, disconnect switches,
inverters, and metallic enclosures should be connected together and grounded at a single service grounding point.

DC FUSES

DC FUSES
All fuses used as overcurrent devices, which provide a point of connection between PV
arrays and collector boxes, must be dc rated. Fuse ratings for dc branch circuits,
depending on wire ampacities, are generally rated from 10 to 100 A. The dc-rated fuses
familiar to solar power contractors are manufactured by a number of companies such
as Bussman, Littlefuse, and Gould and can be purchased from electrical suppliers.
Various manufacturers identify the fuse voltage by special capital letter designations. The following are a sample of time-delay type fuse designations used by various manufacturers.

Grid-tied Solar Systems with Backup Power

As grid outages become more common, there is a growing desire for solar electric systems that provide power during utility power outages. For the safety of line workers, grid-tied solar electric systems must not feed power back into the utility lines during an outage. Batteryless inverters simply shut down when the power goes out. Grid-tied battery based inverters include a transfer switch to isolate them from the grid and use a battery bank to supply power to loads designated for backup and connected to a separate output from the inverter.
There are several ways to design and deploy inverters with backup capability. Means of connecting the backup loads to the system can range from simple to complex. Backup power can be arranged for longer or shorter times depending on the loads and battery bank capacity.

DC coupled PV system – SOLAR SYSTEM
The most common arrangement for grid-tied solar with backup is where the PV array powers a DC charge controller to charge a battery bank. Whenever the battery is fully charged, the voltage rises to a set point and any power available over that voltage is available for use. The inverter output is connected to both the backup (aka critical loads) subpanel, and to the grid intertie in the main electrical panel. Under normal conditions, it functions like any other net metered inverter. During an outage, an automatic transfer switch in the inverter opens the grid interconnect, isolating the building from the utility to prevent back-feeding the local power lines. The inverter then draws from the battery bank to provide AC power to the backup subpanel.

The term “DC coupled” has only come into use recently to distinguish this configuration from “AC coupled” which is a newer arrangement that has come into use.  When starting from scratch, a DC coupled system is typically the most cost-effective and reliable configuration to use. Note however, that the PV array is not managed by the inverter, but by the charge controllers, many of which are limited to 150 VDC input.
Inverters that can be used for DC coupled grid tied systems include the OutBack GVFX, GTFX, and GS (Radian) series, the Schneider Electric XW series, and the SMA Sunny Island series . Any charge controller  can be used with a DC coupled system so long as it is compatible with the solar array  and the battery .

Grid-tie solar AC coupled
In an “AC coupled” system, a batteryless grid-tie inverter is connected to the solar array, while a battery based inverter is used to produce power from the battery bank during a utility outage. In this configuration, the AC output of the grid-tie inverter is connected to the backup (aka critical loads) subpanel rather than the building’s main panel. The backup subpanel is also connected to the AC output of the battery inverter. The AC input of the battery inverter is then connected to the main panel as in a DC coupled system.
Under normal conditions, the batteryless grid-tie inverter is passed through the battery based inverter’s built-in transfer switch, to the main panel and utility intertie, without loss of efficiency. Likewise, grid power can pass the other direction when needed to power the loads in the backup subpanel. During a power outage, the battery inverter’s transfer switch isolates itself from the utility connection and provides AC power to the backup subpanel, drawing energy from the battery bank. The batteryless grid-tie inverter will shut down at the start of a blackout, but will turn back on (after a mandatory 5-minute waiting period) when AC power from the battery inverter is detected and supply AC power to the backup subpanel, and if enough power is available, will be used by the battery inverter to charge the batteries. Note that once the battery bank is fully charged and the loads are served, the batteryless grid-tie inverter will need to be throttled back, diverted or shut down in order to prevent damage to the batteries.
An AC coupled system offers a few advantages compared to the traditional DC coupled system.  The batteryless grid-tie inverter can use the higher voltage from the solar array, reducing the required wire size, and is generally more efficient than a battery based inverter. Additionally, if a direct gird-tie system is already installed and battery backup is added later, it is often more convenient and cost effective to leave the existing system in place. Countering the advantages, AC coupled systems are typically much more expensive and complex to design and only certain inverter technologies can be used in such systems.
Currently the SMA Sunny Island is the only equipment specifically made to be AC coupled (with SMA Sunny Boy inverters) and is fully factory supported. With the exception of high frequency inverters, such as Fronius IG Plus and SMA SunnyBoy HF, most batteryless grid-tie inverter can be made to work in an AC coupled mode. However, most manufacturers cannot provide adequate technical support, and some warranties will become void if the inverter is AC coupled. It’s wise to check first before designing a system. SMA, OutBack, Schneider Electric, and Magnum  all make battery based inverters that can be used in an AC coupled configuration.

Grid tie solar and backup without batteries
The SMA Sunny Boy 3000TL-US/4000TL-US/5000TL-US line of inverters has an Emergency Power Supply option. During a power outage, so long as the sun is shining, power is available from a separate switchable circuit on the inverter at up to 12A at 120 VAC. This works well to recharge cell phones, laptop computers and other appliances with built in batteries, or add your own UPS (Uninterruptible Power Supply) for continuous power when the clouds go over or the sun goes down.

Battery backup separate from solar
It is, of course, possible to have a battery backup system that is separate from the solar grid-tied system. In parts of the world with frequent short outages, many people just install a battery based inverter and battery bank without any PV whatsoever. Similar to a UPS, the battery is kept charged by the inverter from the utility AC power, and during a power outage will supply power from the battery to AC loads. This type of system has no way of being recharged during an outage.

Backup / critical loads considerations
The most common and accepted method of connecting backup loads is through a backup subpanel that serves specific circuits. The backup subpanel is typically installed next to the main panel so that the circuit wiring can be easily transferred from the main panel to the subpanel. These circuits are then automatically powered through the backup system during a utility outage. Note that only complete circuits can be wired this way, not individual appliances. Appliances can occasionally be moved from other circuits onto a backed up circuit or loads can be moved off of backed up circuits if they are not needed during an outage. If it helpful for the end user, unique styles or colors of receptacles can be installed on backed-up circuits.
It is possible to have a backup system power an entire home or building if either the backup system is very large or the loads are unusually low.  This is not often done because it requires a backup system large enough to power all loads in the house. Otherwise, the loads running when the outage occurs may overload the inverter, effectively defeating the backup system’s purpose. It also introduces technical and potential legal complexities as a larger transfer switch and line side tap are typically required.

System sizing – Backup power duration
For a grid-tied battery based system, the sizing of the solar array is much the same as sizing it for a non-battery grid-tie system. The limitations on the solar array are still: avialable installation area, maximum offset of utility power, and budget. Often a solar array sized for grid-tie will be more than large enough during a power outage. For AC coupled systems, the battery based inverter typically needs to be larger than the batteryless grid-tie inverter for best results.
The battery bank size is determined by the length of time and the size of the loads to be run during an outage. Backup systems can be made to supply power for minutes, hours, or days. If outages are brief or if a backup generator is planned, the battery bank only needs to be large enough to carry the loads for a few hours. Most often, a backup time of one half day or multiple days is desired. If there is not much sun, a generator can be run for a few hours per day to keep the battery bank charged. If the system is to be capable of running indefinitely, it should be sized like a true off-grid system.

Equipment

OutBack
The OutBack GVFX and GTFX inverters are 120 VAC only, but two inverters can be wired in series for 120/240 VAC and up to 7.2 kW of power. Only two of these inverters can be used in one system. If using a single inverter, an autotransformer can be used to create a 120/240 VAC output, if needed. The GVFX and GTFX inverters have only a single AC input that is normally connected to the utility via the main house panel or other intertie point. To use a generator with these inverters during a power outage requires an external transfer switch to connect the inverter AC input to the utility or generator. These inverters’ AC connection parameters are very sensitive and they will not connect to most generators. An inverter based generator, like the Honda eui series, is recommended for use with these inverters. OutBack makes a variety of AC and DC breaker enclosures and accessories for their inverters using their FLEXware system. MidNite Solar also makes E-panels for integration of the OutBack inverters.
The OutBack GS Radian 8kW inverter has 120/240 VAC input and output. Multiple GS inverters can be paralleled up to eight units for 80kW capacity. The GS inverter has two AC input circuits, one for the utility connection and one for a backup generator. Both connections are 120/240 VAC. The OutBack GSLC is available for integrating the GS inverters with AC and DC breakers. Many of the FLEXware accessories will also work with GS inverters. GS Radian inverter can be used in a AC coupled systems, but unlike other OutBack inverters, there is no provision to prevent battery overcharging other than using the AUX DC output and a relay to disconnect the batteryless grid-tie inverter when the battery back reaches the maximum voltage. The capacity of the batteryless grid-tie inverter should not exceed 75% of the total battery inverter capacity.

Schneider Electric Conext XW
The Schneider Electric Conext XW inverters output 120/240 VAC in each unit and up to four inverters can be wired in parallel for up to 24kW of power. The XW inverters have two AC input circuits, one for the utility connection and one for a backup generator. Both connections are 120/240 VAC. Available integration panels and accessories from Schneider Electric and/or MidNite Solar and help simplify design and streamline installation.

Conext XW inverters can be used in AC coupled systems, and recent versions include a frequency shift feature for control of the grid-tie inverter for battery charging. When the frequency is shifted out of specification, it causes the grid-tie inverter to drop off line. The capacity of the grid-tie inverter should not exceed 100% of the XW inverter capacity.

SMA 
SMA pioneered AC coupled systems for grid-tie battery backup applications. SMA designs are assumed to be AC coupled using Sunny Boy grid-tie inverters and the Sunny Island for the battery inverter. The SMA Sunny Islandinverters output 120 VAC only, and can be wired in series to make 120/240 VAC power. Up to four Sunny Island inverters can be wired in parallel for up to 24kW of power.  The SMA Smartformer, or a similar autotransformer, can be used to make 120/240 VAC output from a single Sunny Island inverter. The Sunny Island will shed the AC loads to prevent battery over-discharge while continuing to charging the battery bank. It also includes a pre-wired AC distribution board with a bypass switch for direct grid operation, as well as circuit breakers and wire terminals.  The utility connection for the Sunny Island is 120 VAC only. When using two to four Sunny Island inverters, the AC input and output will be 120/240 VAC and an autotransformer is not needed.
The Sunny Island uses frequency shift to control the battery charging from the grid-tie inverter. With most Sunny Boy grid-tie inverters, communication with the Sunny Island inverter will allow for a gradual reduction in power from the Sunny Boy inverter as needed to prevent battery overcharging. Other string inverters will also work with AC coupling, but will shut off and on with frequency shift instead of smoothly backing off the power. New integration panels from MidNite Solar for use with the Sunny Island inverter, include pre-wired and assembled systems to streamline design and installation. The capacity of the Sunny boy inverters can be 200% of the Sunny Island capacity for more flexibility in system sizing and better production on cloudy days or with occasional large loads.
When used with a 120/208 VAC three phase system, multiple trios Sunny Island inverters can be assembled into a system using the Multi-cluster box for a system with up to 72 kW capacity. Each group of three Sunny Island inverters will have a separate battery bank.

Magnum Energy
Magnum Energy MS4024PAE and MS4448PAE inverters are not grid-tie inverters on their own and can only be used in a grid-tied system when AC coupled. The grid-tie inverter provides connection to the grid while the Magnum inverter serves the battery backup system. Both of these inverters have 120/240 VAC input and output without a separate transformer. The Magnum inverters have a single AC input that is normally connected to the utility via the main house panel or other intertie point in a grid tied system. To use a generator with these inverters during a power outage requires an external transfer switch to connect the AC input of these inverters to either the utility or the generator. Magnum inverters use frequency shift to protect the battery bank from being overcharged, but they allow higher voltage than is normally recommended for the battery, so should be used only as a secondary control. Primary control can be provided either with a diversion control to burn off excess production into a heater, or by using the auxiliary contacts on the Magnum RTR router to trip a relay taking the grid-tie inverter off line when the battery reaches a set voltage.
Magnum makes a variety of AC and DC breaker enclosures and accessories for their inverters to streamline design and installation. MidNite Solar makes E-panels for integration of the Magnum inverters, and also full systems designed for AC coupling, including pre-wired and assembled systems. The Midnite AC coupled system uses the RTR relay for battery control and is available with the MS4024PAE inverter. The output of the grid-tie inverter should not exceed 90% of the battery inverter capacity.

Batteries
A battery banks are typically 100 Ah or larger. A 48 volt, 100 Ahr battery bank, when adjusted for inverter efficiency and maximum 80% depth of discharge, will provide about 3.5 kWh of energy over a 20 hour period. The battery bank must obviously be sized to serve the loads, but also must be able to accept the highest possible charge current from the PV array if it is not otherwise regulated.
Battery banks usually consist of one to three parallel strings of batteries up to 225 Ahr each. The MK Deka batteries and the OutBack RE series are both excellent choices and can last up to 10 years in backup applications.OutBack’s integrated battery rack holds up to 3 parallel strings of their RE batteries, and is prewired with a circuit breaker for each parallel string, adding a level of safety not usually found in backup battery banks. MidNite Solar makes a variety of battery enclosures for different battery sizes and quantities. Other racks and enclosures can be found or made for a battery bank as well.
For larger battery banks, the Deka Unigy II battery is available in sizes up to 2,367 Ahrs and can last up to 20 years in backup applications. Each Unigy II battery comes as a complete system with bolt together rack, cell interconnects, covers, and large termination bars. This battery bank consists of cells that are stacked on top of each other up to 6 feet high and can take up surprisingly little floor space.
Flooded batteries are not recommended for backup applications for a variety of reasons. They require much more maintenance in terms of both labor and electrical consumption.  Additionally, the specific siting requirements for flooded batteries often render them impractical for typical residential backup applications.

– Brad Bassett
Application Engineer, AEE Solar

Bencmark PV Software

Tabel benchmark penggunaan PV software untuk design Solar Farm, Tabel skor maksimal diperoleh PV Sol Expert, untuk PV Syst merupakan referensi tengah dengan skor 6,2. Semoga benchmark tersebut bermanfaat untuk referensi pemilihan software design Solar system, baik on grid maupun off grid.

How to Size Your Off-Grid Solar Batteries

If you are designing a solar electricity system and don't have access to the grid, you are going to have to deal with batteries. When you start looking at solar batteries you are going to encounter a little math. Fortunately,  SolarTown is here to guide you through the calculations!

The general goal when designing an off-grid battery bank is to get a system that is big enough to supply all your needs for a few cloudy days, but is also small enough to be charged by your panels. Before you get started here you may want to check out this article. It serves as a good introduction to the solar batteries I'll be talking about:

http://www.solartown.com/learning/solar-panels/solar-battery-storage-systems-if-you-cant-tell-your-agm-from-your-gel

Alright let's get started! Here are the steps to sizing your off-grid system.

Step 1: Calculating Your Amp-hour Needs

1.  Inverter size
To determine the inverter size we must find the peak load or maximum wattage of your home. This is found by adding up the wattage of the appliances and devices that could be run at the same time. Include everything from microwaves and lights to computers and clocks. The sum will tell you which inverter size you need.

Example: A room has two 60 watt light bulb and a 300 watt desktop computer. The inverter size is 60 x 2 + 300 = 420 watts

2.  Daily energy use
Next find the energy used in a day. Figure out how long each electronic device will be run in hours during a day. Multiply the wattage of each device by its run-time to get the energy in watt-hours per day. Add up all the watt-hour values to get a total for your home. This estimate is likely too low as there will be efficiency loses. To get a very rough idea of the real value with system loses, multiply by 1.5. This will help account for decreasing performance when temperature increases.

Example: Light bulbs run for 5 hours a day. Computer runs for 2 hours a day. 120 x 5 + 300 x 2 = 1200 watt-hours. 1200 x 1.5 = 1800 watt-hours

3.  Days of autonomy
Now decide how many days worth of energy you want to store in your battery bank. Generally this is anywhere from two to five.

4.  Battery bank capacity
Finally we can calculate the minimum battery AH capacity. Take the watt-hours per day and multiply them by the number you decided upon in 3. This should represent a 50% depth of discharge on your batteries. Therefore multiply by 2 and convert the kwh result into amp hours (AH). This is done by dividing by the battery voltage.

Example:  You want the battery bank to last three days without recharging and that you use 1.8 kwh per day. As 1.8 x 3 x 2 = 10.8kwh, this is the energy we need from the batteries. Converting this to AH we have to divide by the voltage of your system. This can be 12, 24 or 48 for commercial application. If we choose to use 48V, the minimum AH capacity is then 10 800/48 = 225 AH. Now if you divide by your battery's rating you find the number of batteries you must use.

Step 2: Don't Overcharge Your Batteries!

Once you have sized your battery bank and solar panel array, determining which charge controller to use is comparatively straight forward. All we have to do is find the current through the controller by using power = voltage x current. Take the power produced by the solar panels and divide by the voltage of the batteries.

Example: A solar array is producing 1 kw and charging a battery bank of 24V. The controller size is then 1000/24 = 41.67 amps. Now introduce a safety factor. Multiply the value you have found by 1.25 to account for variable power outputs: 41.67 x 1.25 = 52.09 amps

In our example we would need at least a  52 amp controller. The Flex Max 60 MPPT Charge Controller would fit our specifications.

Step 3:

Battery Wiring – Putting it all together

Before buying your batteries you need to figure out how many you need. Wiring is going to play a major role in determining this number. The goal is to find a configuration that produces target AH and voltage. There are two methods of wiring components in a circuit: parallel and series. In a series configuration the battery voltages add up while in parallel, current adds up.
Series and parallel connections can be combined to produce the voltage and AH that you require. Just remember:

      Series    →  voltage adds, current  does not
      Parallel  → current  adds, voltage does not

Previously we claimed that you could find the number of batteries you would need by dividing the AH capacity of your system by the AH rating of your batteries. This actually depends on how you wire together your system. Also remember that if a used battery is connected in parallel to a new one, it will degrade the fresher battery decreasing the lifespan of the whole system. Some people say that ideally you should just use a long line of batteries connected in series for your battery bank. Unfortunately this is not always possible due to voltage and AH requirements.

Step 4: You're Done!

Batteries: Which is best for solar storage?

By Kathie Zipp | August 21, 2015

Interest in energy storage is growing rapidly. It’s not all about living off the grid anymore. Storage helps solve variability issues with renewables. Adding solar batteries to a grid-connected residential project also allows the array to keep providing power to critical loads when the grid is down, instead of having to disconnect and refrain from generating power. Storage can also help commercial consumers reduce peak demand charges, significantly lowering their energy bills. Storage is even used at the utility level to help provide ancillary services to the grid. The need for storage grows as states pass self-consumption legislation.

Batteries in solar applications have to meet the demands of unstable grid energy, heavy cycling (charging and discharging) and irregular full recharging. There’s a variety of battery types fitted for these unique requirements. Considerations for choosing a battery include cost, cycle life and installation and maintenance.

Here’s a look at these aspects of each technology, as well as some best practices when selecting batteries for a solar installation.

Solar battery technologies

Lead acidDeep-cycle, lead-acid batteries have been employed in renewable energy and reliably used in off-grid applications globally for decades.

Cost: Typical deep-cycle, lead-acid batteries cost significantly less than lithium-ion.

Cycling: Valve-regulated lead-acid (VRLA) batteries include absorbed glass mat (AGM) and gel models. Many AGM batteries available in the market are primarily built for dual-purpose or standby applications like emergency backup, but not deep cycling. However, new deep-cycle AGM designs have increased performance and total energy output making them a good choice for renewable energy applications at a lower price point than gel batteries.

In fact, VRLA batteries with added nanocarbon are more resistant to sulfation, which can lead batteries to die over time. The carbon slows sulfation and allows the battery to charge faster and cycle more than traditional lead acid. This makes it a good choice for applications in which the battery is in a partial state of charge, such as energy arbitrage or off-grid.

Replacement/maintenance: Many factors including initial design and ongoing maintenance influence battery life so it’s difficult to put a time frame on when the batteries will need replacement. Flooded lead-acid batteries have to be refilled regularly because the electrolyte that fully submerges the battery plates evaporates during charging. The battery enclosure needs ventilation to keep hydrogen gas from accumulating to dangerous levels.

AGM and gel technologies, however, are recombinant, meaning they internally convert hydrogen and oxygen into water and do not require maintenance. As there is no free acid inside these batteries, they can be installed in any position other than upside down. Because solar applications can be in hard-to-reach or remote areas, the ability to install the batteries and let them operate over long periods without maintenance is a benefit.

Disposal: Proper disposal of lead-acid batteries is important because they are toxic. Thankfully, the automotive industry organized to recycle lead early on. Plastic containers and covers of old batteries can also be neutralized, reground and used in new battery cases. In some cases, the electrolyte is cleaned, reprocessed and sold as battery-grade electrolyte. In other instances, the sulfate content is removed as ammonium sulfate and used in fertilizers. The separators are often used as a fuel source for the recycling process. Old batteries may be returned to the battery retailer, automotive service station, a battery manufacturer or other authorized collection centers for recycling.

Lithium-ionAccording to a U.S. Solar Energy Monitor report, lithium-ion batteries are the most common storage technology, regardless of application. There are three types: pouches such as in smartphones and tablets, cylindrical such as in power tools, and prismatic (which come in various shapes) such as in electronic vehicles. Prismatic types often have corrugated sides, which create air gaps between adjacent cells and can aid in cooling. The prismatic can have applications in solar energy storage, specifically lithium iron phosphate (LFP) batteries.

Cost: Deutsche Bank analysts estimated lithium-ion batteries at about $500/kWh at the end of 2014, but one manufacturer said it’s closer to $750 to $950/kWh. Overall, they are more expensive than lead acid batteries. Part of this cost comes from needing a battery management system to monitor the voltage and temperature of each cell to prevent excessive charging and discharging. A BMS isn’t critical for other technologies like lead acid because the inverter or charger controller can handle the battery charging regime. However, some manufacturers note that, if sized correctly, lithium-ion cells can reduce the cost of peripheral devices like charge controllers, offsetting its higher initial price and lowering cost-of-ownership.

Cycling: Lithium-ion batteries can typically deliver more cycles in their lifetime than lead-acid. This makes them a good choice for applications when batteries are cycled to provide ancillary services to the grid such as energy smoothing or frequency and voltage support. The most important benefit lithium-ion provides for solar is its high charge and discharge efficiencies, which help harvest more energy. Lithium-ion batteries also lose less capacity when idle, which is useful in solar installations where energy is only used occasionally.

Replacement/maintenance: Lithium-ion batteries can be lighter and more self contained than lead-acid batteries, so may be easier to install and change out. They can be wall-mounted and located indoors or outdoors. They are solid, so don’t require refills or maintenance.

Disposal: Lithium-ion batteries can use organic or inorganic cells. Organic-based batteries are free from any toxins. Inorganic-based cells are much more difficult to dispose of. Inorganic lithium-ion is toxic so it must be disposed of properly. Manufacturers encourage recycling, but there is often a price. Spent lithium-ion cells have little commercial value. Lithium-ion manufacturing involves lengthy preparation and purification of the raw material. In recycling, the metal must go through a similar process again, so it’s often cheaper to mine virgin material than retrieve it from recycling.

Flow batteriesRedox flow batteries are emerging as another storage option. Lux Research reports that falling costs will lead to a 360-MWh market in 2020, worth $190 million. The vanadium redox flow battery (VRFB) is the most mature technology in this area.

Cost: VRFB developers say that sourcing vanadium from flyash (a by-product of coal-fired electric generating plants) will reduce costs from over $500/kWh to $300/kWh at scale by 2024. VRFB developers are developing ways to boost power density, which will further drive down costs. Integrated power electronics manage the charging and discharging processes, providing a low cost-of-ownership. But the complexity of flow battery chemistry often requires ancillary equipment such as pumps, sensors, control units and secondary containment vessels. This infrastructure takes up appreciable installation space.  However, one manufacturer has eased the complexity of ancillary equipment by including all required components within the container itself thereby offering a complete built-in solution.

Replacement/maintenance: VRFB manufacturers note the vanadium electrolyte doesn’t degrade over time, so they can last much longer than other technologies. With other technologies, adding more batteries is the only way to increase hours of storage. A benefit of VRFB architecture is that you can increase battery size by simply adding more electrolyte.

Cycling: VRFB developers say the technology has no cycling limitations, and batteries can be charged and discharged completely without impact on their lifespan.

Disposal: The recycled vanadium in flow batteries is not toxic and can be reused repeatedly for other purposes, such as in making steel. Flow batteries contain an aqueous-based electrolyte that can’t get hot or catch fire and thus are intrinsically safe.

Nickel cadmium 
Nickel cadmium or NiCd batteries have been around since the early 1900s. Though they may not have the energy density (the power) of other technologies, they provide long life and reliability without complex management systems.

Cost: Nickel cadmium is relatively inexpensive compared with other technologies.

Replacement/maintenance: NiCd batteries are vented to allow gases to dissipate. They traditionally require some watering, but new designs allow the gases to recombine to form water which makes the battery nearly maintenance free. This, along with the ability to tolerate extreme temperatures, makes these batteries ideal for off-grid applications in harsh environments. They have been used for storage in megawatt-sized projects. .

Cycling: NiCd batteries are rugged batteries with a high cycle life. Some companies promise a service life of up to 20 years.

Disposal: Cadmium is a hazardous material. In fact Europe limits the applications NiCd batteries can be used in. Toxic materials must be removed before the battery is disposed of. NiCd batteries can be recycled, however. The cadmium can be extracted and reused in new batteries. The nickel can be recovered and used to make stainless steel.

Choosing the right battery

Use a sizing calculator
Battery sizing is essential but often overlooked by users and installers. Batteries in PV systems are routinely undersized due to cost or because the system loads were underestimated. It’s important to know the customer’s power needs and correctly plan. Many online calculators provided by battery manufacturers and other software simplifies determining battery capacity for load requirements.

Consider cost of ownership
There are several factors that should be taken into account when determining the total cost of ownership over the life of the battery.
• Price: A battery with a low price is always attractive, but if low price comes at the expense of quality and battery life, the need for frequent battery replacements could boost the cost over time. That’s why it’s important to consider issues other than price when making the decision.
• Capacity: Battery capacity is important because it’s a measure of the amount of energy stored in the battery.
• Voltage: The battery bank voltage must be considered to ensure it matches the system requirements. The battery bank voltage is often determined by the inverter specifications if installing a DC-to-AC system or by the voltage of the loads in a DC system.
• Cycle Life: The most critical consideration is cycle life, which provides the number of discharge/charge cycles the battery can provide before capacity drops to a specified percentage of rated capacity. Batteries from different manufacturers may have the same capacity and energy content and be similar in weight. But design, materials, process and quality influence how long the battery will cycle.

Battery ratings
The nameplate rating on a battery is the fully developed capacity, so it can be misleading to test a battery immediately after it is purchased because it may take up to 100+ cycles for it to reach its full capacity. Beware of batteries that promise full capacity at the time of purchase or those that reach full capacity after only a few cycles. Batteries with a 100+ cycle warm-up will always outlast those touting a high initial capacity.

This article has been updated as of 8/2017.